In the catalytic processing of petroleum feed stocks, it is often desirable to alter the pore structure of the catalyst support in order to accommodate different types of feeds. For example, when processing feed stocks of high metals content, wide-pore supports are used to prevent plugging of the pores by deposition of metals. On the other hand, when processing feed stocks containing no metals or with a low metals content, it may be both technically and economically desirable to use a narrow-pore catalyst support. For purposes of denitrification, narrow-pore catalysts have higher activities and longer lives than catalysts containing large pores which tend to deactivate quickly.